Python Sypherical volume

"Given sphere_radius and pi, compute the volume of a sphere and assign to sphere_volume. Volume of sphere = (4.0 / 3.0) π r3

Sample output for the given program: 4.18878666667"

I am to get the test to pass both when the radius of 1 is calculated and the radius of 5.5. I can get one or the other to work but not both simultaneously. Please assist me in correcting the code so that it will successfully pass the test to calculate sphere_volumes using the two different radius', 1 and 5.5 when I command it to print(sphere_volume)....

This is what I have and isn't working at all when I combine the two radius calculations in the code: